The principal objective of this research is to relate protein structure to function. Our main emphasis has been on the attempt to understand molecular features of protein nucleic acid interactions. We have been attempting to crosslink DNA binding proteins to DNA using ultraviolet light. We have succeeded in doing this with the gene 5 protein specified by bacteriophage fd and fd DNA and have shown that in this case a cysteine residue is linked to thymidine. We have also shown that the gene 32 protein specified by bacteriophage T4 can also be crosslinked to DNA using ultraviolet light but the nature of the linkage is not known. To extend these studies we are incorporating BRDU into DNA and attempting to form covalent links between the BRDU substituted DNA and various proteins that are involved in replication and transcription. We are also studying the amino acid sequence of DNA binding proteins and of coat proteins from various filamentous DNA bacteriophages.